[Ktrace35]

i was in the chevy dealership shooting the shit with one of the mechanics and he asked what was next for me to do to the car. i told him i thinking about putting 20's or 22's on and he said 22's wouldn't fit (people have already proven that wrong) and he said they would have to reprogram the speedometer. is there a way i can figure out how much the speed would change and is it worth reprogramming twice a year? (once for summer wheels, once for winter wheels)

 

[Len McRiddle]

You can figure it out here.

http://www.miata.net/garage/tirecalc.html

 

[Silver LTZ]

i was in the chevy dealership shooting the shit with one of the mechanics and he asked what was next for me to do to the car. i told him i thinking about putting 20's or 22's on and he said 22's wouldn't fit (people have already proven that wrong) and he said they would have to reprogram the speedometer. is there a way i can figure out how much the speed would change and is it worth reprogramming twice a year? (once for summer wheels, once for winter wheels)

If you stay with the same overall diameter you won't have to worry about that. The guys at Discount Tire were great about that when I was wheel shopping. Mine are within .1" of stock so the speedo is 99.9% spot on. If you don't stick with the same diameter it might be off 3 or 4 mph at most. But it will be hard to get 22's that are the same, 20's is about as big as you can go keeping the same overall diameter.

 

[Len McRiddle]

Here is a link to another one than does not require Java run time installed.

http://www.discounttire.com/dtcs/infoTireMath.dos

 

[Ktrace35]

thanks fellas. now i just need to find some shoes i like